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Background: Zinc oxide (ZnO) and graphene oxide (GO) nanoparticles (NPs) have antimicrobial properties. The present study was undertaken to evaluate the effects of incorporating these NPs and their chemical and physical blends on abrasion, translucency, and microhardness of flowable composite resin. Materials and Methods: In the present in vitro study, flowable composite resin samples (Grandio Flow, VOCO, Germany) were evaluated in 5 groups and the sample size was 10 for each group of each experiment (n = 10) as follows: Group 1, without NPs; Group 2, with ZnO NPs; Group 3, with GO NPs; Group 4, containing a physical mixture of GO and ZnO; and Group 5, containing a chemical mixture of GO and ZnO NPs. In all the groups, 1 wt% of the NPs were incorporate into flowable composite resin. Abrasion, translucency, and microhardness of the samples were evaluated. Data were analyzed with analysis of variance, followed by post hoc Tukey's tests at the level of significance of P < 0.05. Results: In Groups 2, 4, and 5 (all the groups containing ZnO), a significant decrease in abrasion and microhardness of flowable composite resin was observed compared to the control group. Incorporation of NPs in all the groups resulted in a significant decrease in translucency compared to the control group. Conclusion: Incorporation of NPs into flowable composite resin resulted in a decrease in translucency. The microhardness was reduced in groups containing ZnO, but the abrasion was also reduced in these groups. The incorporation of GO did not significantly alter the abrasion and microhardness of the composite resin.
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Background: Dentists might face various artifacts (such as triangular-shaped radiolucencies [TSRs]) during the assessment of radiographs and should be able to differentiate them from caries to avoid unnecessary treatments. Materials and Methods: In this cross-sectional study, 109 maxillary second primary molars were evaluated in cooperative children aged 4-9 years, who had distal caries in their maxillary first primary molars. First, TSRs were recorded on periapical radiographs of each maxillary second primary molar's proximal surface. Then, after excavating distal caries in the adjacent teeth "D," a pedodontist examined the mesial surfaces of teeth "E." Chi-square test was used to compare the distribution of caries in different variables, and the kappa coefficient was applied to evaluate clinical and radiographic agreements. A P < 0.05 was considered statistically significant. Results: Forty-four cases were found to be carious both clinically and radiographically, and 54 cases were noncarious by both methods, while for 11 cases, the diagnosis was controversial. No statistically significant difference was found between radiographic and clinical caries detection methods in children whose periapical radiographs contained TSRs, and most of the subjects had similar diagnoses. Value of caries detection sensitivity, specificity, positive predictive value, and negative predictive value in TSRs was 88%, 92%, 90%, and 90%, respectively. Conclusion: Considering high radiographic sensitivity for caries detection in TSRs, clinicians should be more cautious about them being carious or not, and both radiographic and clinical examinations are necessary. Further, to avoid misinterpretation in radiographs, additional education is necessary for young dentists.
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STATEMENT OF THE PROBLEM: Several additives have been introduced to decrease the setting time of MTA (mineral trioxide aggregate). For clinical applications, it is essential to investigate the biocompatibility of these materials. PURPOSE: The present study evaluated the tissue response to MTA that has been separately mixed with citric acid, calcium lactate gluconate (CLG), and Na2HPO4. MATERIALS AND METHOD: In this experimental study Twenty one Wistar rats were divided into three groups of 7, 14 and 30 days follow up periods. Sterile polyethylene tubes were subsequently filled with MTA separately mixed with distilled water, 0.1% citric acid, 0.43% calcium lactate gluconate (CLG) and 15% Na2HPO4 and afterwards implanted subcutaneously. Empty tubes were implanted as negative control. At the end of their respective periods, the animals were sacrificed by anesthetic overdose and a biopsy was performed. The inflammatory responses were scored, classified and statistically analyzed using Kruskal-Wallis and Man-Whitney tests. Statistical significance was defined as p< 0.05. RESULTS: There was no significant difference between test groups in any time period after implantation but the mean values of inflammatory responses were significantly more than that of the negative control group (p> 0.05). The mean values of inflammatory responses were decreasing over time in all test groups. These values did not significantly differ in any group except the CLG and Na2HPO4 groups. CONCLUSION: The inflammatory responses induced by MTA mixed with citric acid and MTA mixed with Na2HPO4 were comparable to that of the control MTA. MTA mixed with CLG provoked a moderate-to-severe inflammatory response at 7 days after implantation, so further study is required before clinical application of this cement.
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INTRODUCTION: One of the biggest disadvantages of dental amalgam is that gaining its ultimate strength is a slow process. The use of a rapid-setting amalgam with high early compressive strength could be a better option in preventing early fractures in pediatric dentistry. The aim of this study was to determine the effect of diode laser irradiation on compressive strength of dental amalgam. METHODS: A case-control study was performed on 180 amalgam samples made at the Tehran Dental Material Research Center in 2014. Fifteen and thirty minute compressive strength of regular setting and fast setting amalgams were measured as control. In case groups, the samples were irradiated by 810nm diode laser with power of 1 and 2 watt and in pulsed and continuous mode, and compressive strength was measured after 15 and 30 minutes. Statistical analysis was performed with SPSS 18 using one and two way ANOVA and Scheffe multiple comparisons test and p<0.05 was considered significant. RESULTS: Numerous kinds of laser irradiation led to a significant increase in compressive strength compared to regular setting control groups. Fifteen minutes-compressive strength of regular-setting amalgam irradiated by 2 watt laser was significantly more than fast-setting control group (p<0.05). CONCLUSION: Irradiation by 810nm diode laser can significantly increase the compressive strength of dental amalgam especially in the first 15 minutes.
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AIMS AND OBJECTIVES: Dental erosion is a common disease in children. Food diets, due to high amounts of juice, soft drinks, chewing gum, and acidic chocolate, are one of the most important risk factors in erosive processes among children. The aim of this study was to evaluate the effect of candy and chocolate on the microhardness of tooth enamel. MATERIALS AND METHODS: Two types of popping candy and one type of popping chocolate were used in this study. Thirty-three healthy permanent premolar teeth and 33 primary incisor teeth (A or B) were selected. Five grams of each popping chocolate or candy was dissolved with 2 ml of artificial saliva. Subsequently, their pH and titrable acidity (TA) as well as microhardness and surface roughness of enamel were examined in the laboratory. Data were analyzed and evaluated Released 2011. IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY through independent t-test, paired t-test, Tukey test, and ANOVA. RESULTS: The results of this study showed that only the pH of the candies was below the critical pH of the enamel (5.5) and their TA was B = 0.20 and C = 0.21. The most significant effect on the enamel microhardness of the permanent and primary teeth was by the following types of candy: orange flavor (C), strawberry flavor (B), and chocolate (A), respectively. This difference was significant (P < 0.001) and the surface roughness increased after exposure. CONCLUSIONS: This study showed that popping chocolate and candy reduces microhardness of enamel.
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INTRODUCTION: Preventive resin restorations (PRR) are the conservative choice for the most common carious lesions in children. Thus, new age flowable resin composites with higher filler content are readily used. The aim of this study was to evaluate the microshear bond strength and microleakage of two flowable resin composites containing different percentages of nano zinc oxide (NZnO) particles, which have proven to have antimicrobial properties. METHODS: This experimental in-vitro study was carried out in the Dental Material Research Center of Babol University of Medical Sciences in 2015. One nanohybrid and one nanofill flowable resin composite were chosen and modified with the incorporation of 1% and 3% Wt NZnO particles. Six groups (n=10, 0%, 1%, and 3%) of resin composite sticks on dental enamel (2×2mm) were prepared to be placed in the microtensile tester. The microshear bond strength magnitude (MPa) was recorded at the point of failure. A class I box (3×0.8×1 mm) was prepared on 60 premolars and filled using the resin composites (6 groups, n=10). The specimens were immersed in a 5% basic fuschin solution and sectioned bucco-lingually to view the microleakage using a stereomicroscope. One-way ANOVA and Tukey tests for microshear and Wilcoxon and Kruskal-Wallis tests for microleakage were used to analyze the data in the IBM SPSS Statistics version 22 software. RESULTS: The bond strength of the 3% clearfill group significantly decreased while no significant change occurred in the bond strength in other groups. The Z-350 group had significantly lower microleakage as nanoparticles increased. No significant difference was observed in the clearfill group. CONCLUSION: Up to 3% Wt incorporation of NZnO particles will not diversely alter the bond strength, but it will be beneficial in providing antimicrobial effects with lower microleakage rates.
